Oil shield as part of crankcase for a scroll compressor

ABSTRACT

A hermetic scroll-type compressor including a housing having a motor mounted therein. A compression mechanism is also mounted in the housing and is operatively coupled to the motor. The compression mechanism is secured to a crankcase having a shield surface integrally formed thereon. A suction tube is provided having an outlet end mounted in the housing. At least a portion of the shield surface is substantially aligned with the outlet end such that an oil and refrigerant gas mixture entering the housing via the suction tube impinges upon the shield surface, whereby oil separates from the mixture.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to scroll compressors, and more particularly to an oil shield for directing and separating oil from suction pressure fluid entering the compressor.

[0002] In general, a scroll compressor includes a compressor housing having a suction gas tube with an outlet end mounted in the housing. The suction pressure fluid entering the compressor is an oil and refrigerant mixture which passes through the suction gas tube outlet end into the compressor housing. The suction gas tube is commonly spaced from the suction inlet of the compression mechanism to prevent the substantial amount of oil entrained in the incoming refrigerant from being drawn into the compression mechanism.

[0003] In some compressors, the oil and refrigerant gas mixture disperses throughout the housing if it is not directed toward a particular portion of the compressor upon entering the compressor housing. The oil and refrigerant mixture then comes into contact with several of the compressor components including the crankcase, counterweight, and motor.

[0004] A problem with allowing the oil and refrigerant mixture to disperse once it enters the compressor housing is that the fluid flowing over the motor may be insufficient to cool the motor. Further, a portion of the oil entrained in the refrigerant needs to be separated therefrom to prevent substantial amounts of oil from entering the compression mechanism with the suction pressure refrigerant gas. The entrained oil clings to the compressor components as it comes into contact therewith, and eventually drips into the oil sump formed in the bottom of the housing. However, rotation of the crankshaft, counterweight, and motor causes the oil collected thereon to be thrown therefrom toward the inside of the compressor housing. This further delays the collection of oil as it takes time for the oil to collect and drip into the oil sump.

[0005] Conventionally, a baffle or oil shield may be mounted to the interior of the compressor housing, being located over and extending substantially above the suction gas tube. One example of a baffle or oil shield is described in U.S. Pat. No. 5,055,010 to Logan. The shield is attached to the inner surface of the housing by projection welding, for example. As the refrigerant and oil mixture enters the compressor housing, it comes into contact with the oil shield. The oil in the mixture clings to the shield and collects thereon. The collection of oil then drips down into the oil sump in the compressor housing. A substantial portion of the refrigerant, now substantially void of entrained oil, is directed toward the suction inlet of the compression mechanism. A smaller portion of the refrigerant is directed downwardly over the motor to cool the motor.

[0006] A problem with the previously used oil shields is that the shield is a separate compressor component, thus increasing the cost of the compressor. Further, the cost of assembly increases as the oil shield has to be secured to the inner surface of the housing.

[0007] It is desired to provide a cost effective oil shield for directing incoming suction pressure fluid and separating oil from the fluid.

SUMMARY OF THE INVENTION

[0008] The present invention relates to a hermetic scroll compressor having an oil shield surface integrally formed with the compressor crankcase. The oil shield surface is positioned above the outlet of the suction gas tube mounted in, and opening into, the compressor housing. A mixture of oil and suction pressure refrigerant gas enters the compressor housing through the suction gas tube and contacts the oil shield surface. A substantial portion of the oil in the mixture clings to the oil shield surface and is separated from the gas. The oil collecting on the oil shield surface drips down to an oil sump formed in the lower portion of the compressor housing. A portion of the refrigerant, being substantially free of oil, is directed by the oil shield surface into the inlet of the compression mechanism and over the motor to cool the motor.

[0009] The present invention provides a hermetic compressor including a housing having a motor and a compression mechanism mounted therein. The motor and compression mechanism are operatively coupled. The compression mechanism is secured to a crankcase having a shield surface integrally formed thereon. A suction tube is provided having an outlet end mounted in the housing with at least a portion of the shield surface being substantially aligned with the outlet end. An oil and refrigerant gas mixture enters the housing via the suction tube and impinges upon the shield surface, whereby oil separates from the mixture.

[0010] The present invention also provides a hermetic compressor including a housing having a motor and a compression mechanism mounted therein. The motor and the compression mechanism are operatively coupled. A crankcase is mounted in the housing and is located between the compression mechanism and the motor. A shield surface is integrally formed on the crankcase, wherein an oil and refrigerant gas mixture being introduced into the housing impinges upon the shield surface and the oil is thereby separated from the mixture.

[0011] The present invention provides a method of separating an oil and refrigerant gas mixture entering a hermetic compressor having a housing with a motor mounted therein, a crankcase mounted atop the motor, and a compression mechanism operatively associated with the motor. The method includes drawing refrigerant gas entrained with oil into the compressor through a suction gas tube mounted in the housing; and directing the refrigerant gas entrained with oil into contact with a shield surface integrally formed with the crankcase, the oil clinging to the shield surface and the refrigerant being directed over the motor mounted in the compressor housing and into the compression mechanism.

[0012] One advantage of the present invention is that the oil shield surface is integrally molded with the crankcase, thus reducing the number of compressor components.

[0013] A further advantage of the present invention is that the assembly step of welding the shield to the inner surface of the compressor housing is eliminated, thus reducing the cost of assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above-mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent when the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

[0015]FIG. 1 is a sectional view of a compressor assembly in accordance with the present invention;

[0016]FIG. 2 is a perspective view of a crankcase of the compressor assembly shown in FIG. 1; and

[0017]FIG. 3 is a top plan view of a crankcase of FIG. 2 shown mounted in the compressor housing.

[0018] Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent an embodiment of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Referring to FIG. 1, hermetic scroll compressor 10 includes housing 12 formed from main shell 14, top end cap 16, bottom end cap 17, and base plate 18. End cap 16 is welded at 15 to the upper end of main shell 14 and separator plate 21. Base plate 18 is provided with annular support 19 for supporting compressor 10 in a substantially vertical orientation. Base plate 18 is welded at 15 to the lower end of bottom end cap 17 which is in turn welded to main shell 14.

[0020] Separator plate 21 divides housing 12 into discharge chamber 90 and suction pressure chamber 94 in which motor 20 is mounted to main housing shell 14 by being, e.g., interference or shrink fitted therein. Motor 20 includes stator 24 located in surrounding relationship of rotor 26. Rotor 26 is provided with central aperture 28 in which drive shaft 30 is interference fitted for rotation with rotor 26. The lower end of drive shaft 30 is rotatably supported in outboard bearing 36 secured to the lower end of main shell 14 by interference fit. The upper end of drive shaft 30 is rotatably supported in aperture 34 formed in crankcase 32 which is fixedly mounted onto upper surface 23 of stator 24. The upper end of drive shaft 30 engages compression mechanism 22 which is mounted atop crankcase 32 by screws 40. Drive shaft 30 rotates with rotor 26 to drive compression mechanism 22 which in turn compresses refrigerant fluid located in the compression mechanism.

[0021] Compressor 10 is a scroll-type compressor with compression mechanism 22 including fixed scroll member 42 and orbiting scroll member 44. Fixed scroll member 42 and orbiting scroll member 44 includes flat plates 46, 50, respectively, having scroll wraps 48, 52 extending therefrom. When fixed member 42 and orbiting member 44 are assembled, scroll wraps 48 and 52 intermesh, creating a plurality of compression chambers 54 therebetween. Orbiting scroll member 44 is positioned between crankcase 32 and fixed scroll member 42 such that back surface 56 of orbiting scroll member plate 50 is in contact with thrust surface 58 of crankcase 32. Annular hub 60 extends from back surface 56 of plate 50 having cavity 62 formed therein in which bearing 64 and roller 66 are located. Hub 60, bearing 64, and roller 66 are received in cavity 65 formed in crankcase 32. Bearing 64 surrounds roller 66 which is provided with aperture 67 to receive eccentric 68 integrally formed at the end of drive shaft 30 to drivingly couple compression mechanism 22 and drive shaft 30.

[0022] The operation of compressor 10 includes motor 20 being electrically energized in a conventional manner, thus inducing rotation of rotor 26 and in turn drive shaft 30. Suction pressure refrigerant gas is drawn into suction pressure chamber 94 defined by separator plate 21 and compressor housing 12 to supply compression mechanism 22 as will be discussed further below. As drive shaft 30 rotates, orbiting scroll member 44 orbits relative to fixed scroll member 42. The orbital movement of orbiting scroll member 44 causes compression chambers 54 to vary in size, thus compressing the suction pressure gas refrigerant to a higher, discharge pressure. The discharge pressure gas is exhausted from compression mechanism 22 through port 88 formed in flat plate 46 of fixed scroll member 42. The discharge pressure gas enters discharge chamber 90 defined by end cap 16 and exits compressor 10 through discharge gas tube 92 to enter the remainder of a refrigeration system (not shown).

[0023] Referring to FIGS. 2 and 3, crankcase 32 includes main body portion 69 in which aperture 34 and cavity 65 are formed. A plurality of legs 70 are circumferentially spaced about the periphery of main body portion 69 extending downwardly therefrom. Legs 70 are connected to main body portion 69 by webs 71 which radially extend from main body portion 69. Upper portion 73 of legs 70 extends slightly above thrust surface 58 of main body portion 69 and has flat surfaces 72 with aperture 74 formed therein. When compressor 10 is assembled, fixed scroll member 42 of compression mechanism 22 is in contact with flat surfaces 72. Screws 40 are then used to engage both fixed member 42 and apertures 74 of crankcase 32, encasing orbiting scroll member 44 between the crankcase and fixed member, and securing compression mechanism 22 to crankcase 32. Lower portion 75 of legs 70 extend downwardly past the lower end of main bearing portion 69 of crankcase 32 and are provided with flat surfaces 76 (FIG. 1) which are in contact with upper surface 23 of stator 24. Legs 70 are secured to stator 24 using any suitable method. One such method may include using threaded fasteners that pass upwardly through the entire length of stator 24 and engage legs 70. Legs 70 are elongated to space compression mechanism 22 above motor 20.

[0024] Referring to the Figures, integrally formed with crankcase 32, between a pair of adjacent legs 70 is oil shield surface 78. The upper edge of oil shield surface 78 is substantially flush with flat surfaces 72 of the adjacent legs 70 between which shield 78 is formed. Oil shield surface 78 extends downwardly a predetermined distance so as to be positioned over outlet end 82 of suction gas tube 80 (FIG. 3) mounted in compressor housing 12. An oil and refrigerant mixture passes through outlet end 82 as it enters compressor 10 and comes into contact with surface 84 of oil shield surface 78. When the mixture hits surface 84, oil entrained in the refrigerant clings to oil shield surface 78. The oil collects on surface 84 and eventually drips onto motor 20. The oil flows downwardly around motor 20 to sump 86 (FIG. 1) formed in the lower end of housing 12. A small portion of the suction pressure refrigerant, substantially free from oil, is directed downwardly over motor 20 to cool motor. The remainder of the suction pressure refrigerant gas is directed upwardly into compression chambers 54 in compression mechanism 22 where it is compressed to discharge pressure.

[0025] While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. 

What is claimed is:
 1. A hermetic scroll-type compressor comprising: a housing; a motor mounted in said housing; a compression mechanism mounted in said housing, operatively coupled to said motor; a crankcase, said compression mechanism secured to said crankcase; a shield surface integrally formed on said crankcase; a suction tube having an outlet end mounted in said housing, at least a portion of said shield surface being substantially aligned with said outlet end; and wherein an oil and refrigerant gas mixture enters said housing via said suction tube, said oil and gas mixture impinging upon said shield surface, whereby oil separates from said mixture.
 2. The hermetic scroll-type compressor of claim 1 wherein refrigerant gas having oil separated therefrom is directed by said shield surface toward said motor.
 3. The hermetic scroll-type compressor of claim 1 wherein refrigerant gas having oil separated therefrom is directed by said shield surface toward said compression mechanism.
 4. The hermetic scroll-type compressor of claim 1 wherein the oil separated from said oil and refrigerant gas mixture collects on said shield surface, said collected oil draining toward a sump formed in said housing.
 5. The hermetic scroll-type compressor of claim 1 wherein said crankcase has a plurality of support legs, said shield surface being formed between a pair of adjacent said support legs.
 6. A hermetic scroll-type compressor comprising: a housing; a motor mounted in said housing; a compression mechanism mounted in said housing, operatively coupled to said motor; a crankcase mounted in said housing and disposed between said compression mechanism and said motor; a shield surface integrally formed on said crankcase; and wherein an oil and refrigerant gas mixture being introduced into said housing impinges upon said shield surface and the oil is thereby separated from said mixture.
 7. The hermetic scroll-type compressor of claim 6 further comprising a suction tube having an outlet end mounted in said housing, said outlet end opening into the housing, said shield surface positioned above said outlet end, the mixture being introduced into said housing through said suction tube.
 8. The hermetic scroll-type compressor of claim 6 wherein refrigerant gas having oil separated therefrom is directed by said shield surface toward said motor.
 9. The hermetic scroll-type compressor of claim 6 wherein refrigerant gas having oil separated therefrom is directed by said shield surface toward said compression mechanism.
 10. The hermetic scroll-type compressor of claim 6 wherein the oil separated from said oil and refrigerant gas mixture collects on said shield surface, said collected oil draining toward a sump formed in said housing.
 11. The hermetic scroll-type compressor of claim 6 wherein said crankcase has a plurality of support legs, said shield surface being integrally formed with said crankcase between a pair of adjacent said support legs.
 12. A method of separating an oil and refrigerant gas mixture entering a hermetic compressor having a housing with a motor mounted therein, a crankcase mounted atop the motor, and a compression mechanism operatively associated with the motor, the method comprising: drawing refrigerant gas entrained with oil into the compressor through a suction gas tube mounted in the housing; and directing the refrigerant gas entrained with oil into contact with a shield surface integrally formed with the crankcase, the oil clinging to the shield surface and the refrigerant being directed over the motor mounted in the compressor housing and into the compression mechanism.
 13. The method of claim 12 wherein the oil collecting on the shield surface drains to an oil sump formed in the lower portion of the compressor housing. 